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<script>
    // 斐波那契数列 黄金比例数字
    // 1 1 2 3 8 ...
    function fib(n) {
       if([1,2].includes(n)) return 1
       return fib(n-2) + fib(n-1)
    }
    const res = fib(4)
    console.log(res)
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